Water resources constitute mainly surface and groundwater, with rainfall being the basic source. The environmental concerns pertaining to water resources centre around water resource management, specifically relate to both quantity and quality issues. The main issues of concern are conservation of existing water resources and prevention of further degradation and depletion. The associated issues include rejuvenation of degraded traditional surface water bodies, enhancing the availability of water through water harvesting measures, and recharge of ground water resources. More important is the judicious and economic use of both ground and surface water for agricultural, industrial and domestic purposes. Karnataka is subjected to repetitive droughts. The National Irrigation Commission has identified 12 districts and 88 taluks in the state as chronically drought affected.
The mean annual rainfall in the state is 1355 millimeters with more than 73 per cent of it being received from the South-West monsoon. In the period between 1970-2003, deficit rainfall was recorded on 22 occasions and the highest deficit of 55 percent was observed in 1983. Annual rainfall variations across agro-climatic zones in the state are too wide, ranging from 585 millimeters in the northern dry zone to 3893 millimeters in the coastal zone. More than 75 percent of the land in majority of the districts in the state is rainfed.
It is estimated that poor quality and inadequate quantity of water accounts for about 10 percent of the total burden of disease in the state. Waterborne diseases occur mainly due to lack of safe drinking water and sanitation facilities. In india every year large number of deaths of children under the age of five is attributed to poor quality of drinking water. Apart from health effects, inadequate quantity of water supply and sanitation services leave adverse impacts on the environment mainly leading to contamination of soil and water due to stagnation of sewage (Government of Karnataka, Task Force on Health, 2001). A recently published World Health Organisation report places diarrhoel diseases at sixth place in the list of global killers and third in the list of morbidity.
According to the World Health Organisation and United Nations Children’s Education Fund (2000) estimates globally, 1.1 billion people lack access to any form of improved water supply within 1 kilometer of their home and 2.4 billion people lack access to some form of improved disposal of excreta.
Groundwater is the major source of drinking water in the state and in rural areas over 90 percent of the drinking water supply schemes are based on ground water. Of the 208 urban local bodies under the Karnataka Urban Water Supply and Drainage Board, 151 depend on river water whereas 47 depend on ground water.
Groundwater levels are fast declining in the state with 34 taluks considered as critical due to over exploitation. Besides, lacunae associated with operation, maintenance and poor distribution systems, also add to the problem. All these pressures limit the availability of safe drinking water.
Bellary, Bangalore, Bijapur, Tumkur, Kolar and Chitradurga are considered as hotspots for drinking water supply as they show all the three problems of inadequate water supply, declining groundwater level and poor water quality. Dharwad has problem of both inadequate water supply and declining groundwater level. Chamarajnagar and Haveri have been listed as hotspots for inadequate water supply and poor water quality.
Basin wise presentation of Hotspots
|Problems||Krishna Basin||Cauvery Basin||Godavari Basin||West Flowing River Basin||Other Basins (Palar, South and North Pennar)|
|I. Inequity & inadequacy|||||||||||
|Pressure on existing water resource surface||Dharwad, Bellary, Bagalkot, Bijapur, Tumkur, Gulbarga, Belgaum, Haveri||Bangalore (U), Kodagu, Hassan, C.R.Nagar|| ||Uttar Kannada||Kolar|
|II. Inefficiency in water use|||||||||||
|Salinity and waterlogging||Bellary, Bijapur, Chitradurga, Raichur, Gulbarga, Dharwad, Shimoga, Belgaum, Davangere||Bangalore (U), Mysore||Bidar (Chukinala)||Kali, Pavenje, Netravati, Gurpura (UK &DK) D.Kannada, U.Kannada|| |
|III. Deteriorating water quality|||||||||||
|Surface Water||Davangere (Tungabadra river Davangere and harihar), Shimoga (Bhadra river-Bhadrvathi & Thirthahalli), Bellary & Koppal (TB river), Bagalkot (Krishna river)||Mandya (Hebbal river) Bangalore (Arkavathi- Kanakapura town), Mysore (kabini river-Nanjangud & Cauvery-Srirangpattana and K.R.Nagar) C.R.Nagar (Cauvery-Kollegal)|| ||Uttar kannada (kali river-Dandel), Dakshina kannada (Netravati & Sullia)|| |
|Ground Water||Tumkur, Chitradurga, Gadag, Bagalkot, Davanagere, Daharwad, Haveri, Bellary||Bangalore (R&U), Mandya, Tumkur (Kunigal, C.R.Nagar)|| || ||Kolar|
|Seepage of Fertilizer and Pesticides||Raichur, Koppal, Belgaum, Dharwad, Chikkamangalore, Shimoga, Bellary||Bangalore (R&U), Mysore, Kodagu, Mandya, Hassan|| ||D.Kannada||Kolar|
|IV. Depleting ground water resource|||||||||||
|Decline in depth and low water table (1990 –2000) & 2002||Bagalkot, Bellary, Chitradurga, Haveri, Belgaum, Gadag, Davangere, Tumkur, Dharwad, Koppal, Gulbarga||Chamrajnagar, Bangalore (R&U), Hassan, Mandya||Bidar|| ||Kolar|
|V. Drought prone area-need for watershed treatment|||||||||||
| ||Chitradurga, Tumkur, Dharwad, Gulbarga, Haveri, Gadag, Bellary, Bijapur||Bangalore (R), Mysore|| || ||Kolar|
|VI. Siltation in reservoir, river beds & estuaries|||||||||||
| ||Belgaum (Ghataprabha & Malaprabha reservoir); Bellary (Tungabhadra reservoir), Shimoga (Bhadra reservoir)|| || ||Linganmakki reservoir (Shimoga), kali (U.K) Netravati & Gurpur (D.K)|||